Like C++, PHP Namespaces are the way of encapsulating items so that same names can be reused without name conflicts.
- It can be seen as an abstract concept in many places. It allows redeclaring the same functions/classes/interfaces/constant functions in the separate namespace without getting the fatal error.
- A namespace is a hierarchically labeled code block holding a regular PHP code.
- A namespace can contain valid PHP code.
- Namespace affects following types of code: classes (including abstracts and traits), interfaces, functions, and constants.
- Namespaces are declared using the namespace keyword.
A namespace must be declared the namespace at the top of the file before any other code – with one exception: the declare keyword.
php
<?php
namespace MyNamespaceName {
function hello()
{
echo 'Hello I am Running from a namespace!';
}
}
?>
If namespace is declared globally, then declare it without any name.
php
<?php
namespace {
}
?>
Multiple namespaces can be declared within a single PHP code.
php
<?php
namespace MyNamespace1 {
}
namespace MyNamespace2 {
}
namespace {
}
?>
A namespace is used to avoid conflicting definitions and introduce more flexibility and organization in the code base. Just like directories, namespace can contain a hierarchy know as subnamespaces. PHP uses the backslash as its namespace separator.
Example:
php
<?php
namespace MyNamespaceName;
function hello()
{
echo 'Hello I am Running from a namespace!';
}
hello();
namespace\hello();
?>
Aliasing in Namespaces
Importing is achieved by using the ‘use’ keyword. Optionally, It can specify a custom alias with the ‘as’ keyword.
Example:
php
<?php
namespace MyNamespaceName;
require 'project/database/connection.php';
use Project\Database\Connection as Connection;
$connection = new Connection();
use Project\Database as Database;
$connection = new Database\Connection();
?>
It is possible to dynamically call namespaced code, dynamic importing is not supported.
php
<?php
namespace OtherProject;
$title = 'geeks';
require 'project/blog/title/' . $title . '.php';
use Project\Blog\title\$title;
?>
Reference : http://php.net/manual/en/language.namespaces.php
My Personal Notes
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